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uniq for unsorted data

Terminal - uniq for unsorted data
awk '!_[$0]++{print}'
2009-02-06 09:52:35
User: dz
Functions: awk
3
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uniq for unsorted data
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Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives

Know a better way?

If you can do better, submit your command here.

What others think

Maybe I'm missing something, but:

a - I can't see how this works

b - it doesn't seem to work

...Create 3 line file test.txt:

'$ cat test.txt:

1

3

2

'$ awk '!_[$0]++{print}' test.txt

1

3

2

Am I being thick?

Comment by g__j 223 weeks and 5 days ago

How about:

sort -u
Comment by systemj 223 weeks and 5 days ago

g__j: it does 'uniq' but without requiring (or doing) sorting;

cat >test

1

3

2

3

1

awk '!_[$0]++{print}' < test

1

3

2

You can actually shorten it to:

awk '!_[$0]++'
Comment by porges 223 weeks and 5 days ago

>>How about:

>>sort -u

I think this has several advantages:

* No need for the overhead of a sort

* Can be embedded in an awk conditional statement. for example:

printf "a\nb\na\nc\na\nc\n" | awk '{if(!_[$0]++){print}}'

* Can be inverted. To show only values that have been seen before. For example:

printf "a\nb\na\nc\na\nc\n" | awk '{if(_[$0]++){print}}'
Comment by unixmonkey3280 208 weeks and 2 days ago

Your point of view

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